ASTM A671 EFW Pipes & Tubes

ASTM A671 - Standard Specification for Electric Fusion Welded Steel Pipe for Atmospheric and Lower Temperatures

ASTM A671 is a standard developed by the American Society for Testing and Materials (ASTM International). This standard applies to steel pipes manufactured by the electric fusion welding (EFW) process, mainly used in pressure vessels, piping systems and other critical applications in normal and low temperature environments.

Scope of Application:

Pressure pipes, storage tanks, etc. used for low or normal temperature services, commonly used in oil, gas, chemical and other industries.
The working temperature is usually not less than -50°F (-45°C), depending on the steel grade and impact test requirements.

Different class categories (such as CL22) are divided according to manufacturing processes, inspection requirements and allowable stress levels, and have strict requirements on welding quality, non-destructive testing, etc.

Specifications and Materials:

Key parameters of ASTM A671 EFW pipe:

Parameter	Requirement
Outer Diameter	16 – 72 in. (406 – 1829mm)
Wall Thickness	6.4 – 50.8mm (heavier walls require mill review)
Common Classes	CL12, CL22, CL32, CL33
Common Grades	CC60, CC65, CC70, CD70, CF66
Class Number Meaning	Heat treatment, radiography and pressure test level
Grade Number Meaning	Minimum yield strength (ksi)
Example	CC60 = 60 ksi (≈415 MPa)

Material Grades:

A671 CC60 is a common carbon steel with specific carbon, silicon and manganese contents. A671 CC65 and CC70 are also common carbon steels, while A671 CD70 is a manganese silicon steel. The A671 standard also covers nickel steels, such as A671 CF66 and CF71.

Chemical Composition:

ASTM A671 steel pipe is made of pressure vessel quality steel plate. Chemical composition varies by grade. The table below lists typical requirements for common carbon steel grades:

Chemical composition varies by grade. Other alloying elements (Ni, Cr, Mo, V) may be added to some grades to improve low-temperature toughness. 

Each element plays a specific role in ASTM A671 steel: carbon (C) affects strength and weldability; manganese (Mn) improves strength and toughness; silicon (Si) is used for deoxidation; sulfur (S) and phosphorus (P) are strictly limited to avoid hot and cold brittleness.

Mechanical Properties:

Mechanical properties of ASTM A671 pipe vary by grade and heat treatment class. Common grades include CC60, CC65 and CC70. The number indicates the minimum yield strength in ksi — CC60 means 60 ksi (≈415 MPa). Key requirements for common grades are summarized below:

Grade	Yield Strength (YS) min, MPa	Tensile Strength (TS), MPa	Elongation min, %
CC60	220	415–550	25
CC65	240	450–585	23
CC70	260	485–620	21

Impact toughness: Charpy V-notch test at -45°C may be required for some grades. Mechanical properties vary by grade and heat treatment class.

Class Comparison Table

The Class number in ASTM A671 defines the heat treatment, radiography and pressure test requirements. The table below helps buyers select the right class for their service conditions.

Class	Heat Treatment	Radiography	Pressure Test
12	None	Section 9	Section 8.3
22	Stress Relieved	Section 9	Section 8.3
32	Normalized	Section 9	Section 8.3
33	Normalized	None	Section 8.3

Other classes (10, 11, 13, 20, 21, 23, 30, 31, 40–43, 50–53) follow the same numbering logic: the last digit indicates radiography and pressure test requirements. Contact us for a specific class.

Manufacturing process:

The steel plate is formed into a round tube by J (Joggle)-C (Crimp)-O (Open)-E (Expand) multi-step forming.
The steel pipe is welded by electric fusion welding (EFW) process, and the welds are subject to 100% radiographic testing (RT) or other non-destructive testing (NDT) to ensure quality.

The welding process requires strict control of current, voltage, and welding speed to ensure weld quality.

Test Requirements:

Test	Requirement	Mandatory / Optional
Hydrostatic Test	Each pipe	Mandatory
NDT (RT / UT)	On welds	Mandatory
Impact Test	Charpy V-notch	Optional (by temperature)

Differences from Other Standards:

Similar standards such as ASTM A672 (for high-pressure and high-temperature electric fusion welded pipes), while ASTM A671 focuses more on low-temperature applications.

Unlike seamless pipe standards (such as ASTM A106), A671 is a welded pipe, but it is strictly tested to ensure strength.

Common Application:

●  Cryogenic liquefied gas (LNG) pipelines
●  Petroleum refining equipment

●  Cryogenic pressure vessels in the chemical industry

●  Chemical plant piping

●  LPG storage tanks

●  Air separation units

●  Power plant low-temperature systems

FAQs

Q1: What is the difference between ASTM A671 CC60 and CC65?
A: CC60 and CC65 are both carbon steel grades under ASTM A671. The number refers to the minimum tensile strength in ksi — CC60 means 60 ksi (≈415 MPa) and CC65 means 65 ksi (≈450 MPa). The corresponding minimum yield strengths are 220 MPa and 240 MPa respectively. CC65 offers slightly higher strength, and the choice depends on design pressure, temperature and allowable stress requirements.

Q2: Does ASTM A671 require impact testing?
A: Impact testing is not mandatory for all ASTM A671 pipe. It is required only when the specified grade and service temperature demand low-temperature toughness. In such cases, a Charpy V-notch impact test is performed, typically at -45°C, to verify the material's resistance to brittle fracture.

Q3: What is the difference between ASTM A671 and ASTM A672?
A: Both cover electric fusion welded (EFW) steel pipe, but they serve different service conditions. ASTM A671 is intended for atmospheric and low temperature service, while ASTM A672 is designed for high-pressure and high-temperature applications. The selection depends on the operating temperature and pressure of the piping system.

Q4: What welding process is used for ASTM A671 pipe?
A: ASTM A671 pipe is manufactured by the electric fusion welding (EFW) process. The steel plate is first formed into a round tube by J (Joggle)-C (Crimp)-O (Open)-E (Expand) multi-step forming, then welded longitudinally. The weld is subject to 100% radiographic testing (RT) or other non-destructive testing to ensure quality.

Read more:

●  ASTM A671 vs. ASTM A672 EFW Pipe

●  ERW Pipe vs. HFW Pipe

●  ERW Pipe Thickness Chart & Sizing Guide

●  SAW vs ERW vs EFW – Welded Steel Pipe Comparison Guide

Need ASTM A671 EFW pipe for your project?

We supply CC60/CC65/CC70 grades in Class 12–33, with full MTC and third-party inspection.

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